Manufacture of covers for abrasive tools



March 15, 1938. F. NOWN v 4 ,9 7

MANUFACTURE OF COVERTS FOR ABRASIVE TOOLS Filed Jan; 15, 1937 2Shets-Shee'l; 1

15, 1938. NOWN MANUFACTURE OF COVERS FOR ABRASIVE iOOLS Filed Jan. 15,1937 2 Sheets-Sheet 2 M/l m Patented Mar. 15, 1938 a UNITED STATESPATENT OFFICE MANUFACTURE or COVERS FOR mnmslvn TOOLS I Frank Nown,Leicester, England, assignor to United Shoe Machinery Corporation,Paterson, N. J., a corporation of New Jersey Application January 15,1937, Serial No. 120,772

In Great Britain February 3, 1936 6 Claims. ('01. 51 -278)- 4, 1934 inthe name of Fred Ricks and Ernest Hope. This tool is of the rotary disktype but inasmuch as only the rim portion of the tool is utilized, theabrasive cover'is formed from a strip of abrasive material applied tothe rim portion only of the tool rather than from a relatively largesheet covering the face of the tool.

It is an object of the present invention to provide an improved methodof making such abrasive covers. In accordance with the method shownherein, an abrasive cover for the rim of a rotary driven tool is made bysecuring together the ends of a strip of abrasive material to form aclosed band and in molding the band While in moist condition by theapplication of internal pressure to a desired shape corresponding tothat of the peripheral portion of the tool upon which the cover is to beapplied. According to the method illustrated herein, a strip ofabrasive-coated cloth is prepared with the edges of the strip in biasrelation to the weave of the cloth; the ends of the. strip are thencemented together to form" a closed band with the abrasive coating onthe outside; the band is then moistened and stretched to a desired shapeby expansive pressure applied internally and it is maintained thusstretched until it dries to thedesired shape.

A further object of the invention consists in the provision of animproved apparatus for making such abrasive covers. As shown herein theimproved apparatus. comprises a'ring of rubber adapted to engage theinterior of an abrasive 1 band and means for expanding the ring to causedevice, a ring of resilient metal is interposed between the rubber ringand the expanding means, the ends of the metal ring being in overlappingrelation when the ring is unexpanded and arranged to snap into abuttingrelation'when the rubber ring is expanded to its fullest extent, therebyto maintain the rubber ring expanded when it is removed from the.expanding means. The illustrated apparatus for expanding the rubber ringcomprises a plurality of members constructed and arranged for radialmovementwith respect to a common center, v each of which mem-- bers hasan arcuate bearing surface for engaging the interior of the'ni'etalring, the several nature of the cemented joint;

X-X of Fig. 9;

the ring to stretch the band. In the illustrated members being movedoutwardly in unison by-a cam mechanism. I p

With the above and other objects and features in view the invention willnow be described with reference to the, accompanying drawings and 5pointed out in the claims.

In the drawings,

Fig. 1 is a plan View of a sheet of abrasivecoated woven fabric foldedwith two of its edges cemented together-in overlapping relation, one 1 0corner of the sheet being shown as turned upwardly to indicate thedirection of weave of the material as being bias relatively to the edgesof. the sheet; I

Fig. 2 is a view in end elevation of the sheet 15 shown in Fig. 1,showing also a gage plate which may be used to assist in folding thesheet tothe required size before cementing;

Fig. 3 is a. plan ,vlew indicating a band out from the sheet shown inFig. l; 20 Fig. 4 is. a perspective view showing the band out in Fig. 3after it has been opened out into circular form; v

Fig. 5 is afragmentary view indicating the 25 Fig. 6 is a plan View of aforming or shaping 'member in unexpanded condition;

"with a band thereon after the forming member has been expanded; I

Fig. 10 is a sectional view taken along the line Fig. 11 is aperspective view of a completed cover member Fig. 12 is a plan view ofan apparatus for use in expanding the forming member; and

Fig. 13 is a sectional view taken along the line MIL-XIII of Fig. 12 andshowing a forming member with a band thereon in position to be expanded.

In Fig. 1 is shown a sheet I of woven fabric coated on one. sidewithabrasive and cut in such a manner that the threads of the material, asindicated by the reference character 3, run in bias relation to theedges of the sheet. A pair of opposite edge portions of the sheet havebeen folded in overlapping relation and glued together, a corner of thesheet being shown as turned over merely for the purpose of betterillustration. The folding of the sheet to a predetermined size isreadily accomplished my employing a gage plate 5 (Fig. 2) about whichthe sheet may be folded. As indicated in Figs. 1 and 5, the abrasivecoating has been removed or preferably omitted from the underlyingsurface of the joint, while the overlapping edge extends just beyond theboundary of the under surface which is free of abrasive. We have found ajoint prepared in this manner to be particularly eflicient as regardsresistance towear. In gluing the edge portions of the sheet together itis desirable to subject the sheet to pressure while the glue sets inorder to insure a firm joint. This may readily be accomplished byplacing the assembly shown in Fig. 2 of the abut-- sive sheet I and thegage plate 5 between the platens of a suitable press. After the glue hasset to form a firm joint the gage plate 5 is re-.

in Fig. 4.

An expansible forming member II is used for imparting the desired moldedshape to the band 9. This member, which is shown in unexpanded conditionin Figs. 6 to 8, comprises an annulus 13 of rubber having across-sectional shape in general but not necessarily in exactcorrespondence to the cross-sectional shape of the abrasive tool bodyupon which the completed cover is to be used. Positioned against theinner surface of the annulus is an arcuate steel strip II which extendsaround somewhat more than half the circumference when the forming memberis in unexpanded condition. Also located within the annulus I3 is asecond arcuate steel strip I! which, when the forming member is inunexpanded condition, is longer than th circumference of the adjacentinternal surface of the annulus. The end portions of the strip I! thusoverlap when the forming member is unexpanded. In Figs. 6 and 7 the twoends of the strip H are indicated by the reference characters l9 and 2|.

respectively.

In using the forming member II the band 9 is placed thereon asindicated. in Fig. 8. We have found it desirable that the band 9 shouldisters the completed band will be of the desired shape.

After the band 9 has thus been mounted upon the forming member II, theforming member is expanded by an apparatus which will presently bedescribed. The expansion of the forming member stretches the rubberannulus l3 to the greater diameter shown in Fig. 9. As the formingmember continues to expand, the overlapping ends I! and 2! of the stripl'|.,will finally snap resiliently into abutting relation as shown inFig. 9. The strip I! will thereupon serve to hold the annulus 83 inexpanded condition. The operator, when he so desires, can readilycontract the annulus to its normal condition by flexing it to bring theends l9 and 2| out of abutting relation. The strip l5 appears to assistin insuring that upon expansion of the forming member the ends [9 and 2|will assume and retain an abutting relation.

As a result of the expansion of the forming member the band 9 which, asabove mentioned, will be in moistened or temperedcondition, will bestretched and in the course of such stretching, by reason of the factthat the weave of the material is on the bias, the marginal portions ofthe band will turn inwardly closely to embrace the adjacent portions ofthe annulus l3. This effect is a result of the stretching action anddoes not require molding under pressure between dies. In Figs. 9 and 10the band 9 is shown as having assumed its desired shape. The band 9 ispreferably allowed to remain on the expanded forming member foraboutfrom three to six hours to allow the band to set into its moldedshape. At the end of this period the operator contracts the formingmember. in the manneraboveindicated. The forming member can then beremoved from the completed abrasive cover which is shown in Fig. 11.member is retracted and removed the band 9 does not contract; at least.to any appreciable extent. The abrasive cover will thus have' thepredetermined circumferential size depending chiefly upon the length ofthe strip IT. The size .may to a lesser extent depend upon thecompressibility of the rubber of the annulus l3 but if bands 9 areoriginally formedof the same length and are made upon similar formingmembers in .eachof which the strip is of a uniform length, then therewill be no appreciable variations in the circumferential size of theabrasive covers. A convenient be in moistened or tempered conditionduring the size for abrasive covers for use in operations in shapingoperation and also that the band 9 should the manufacture of shoes issix and one-quarter be slightly smaller circumferentially than the e..,inches diameter made from a d. initially riphery of the forming member.When the band i is moistened it will stretch readily and hence caneasily be drawn manually upon the forming mem.. her. As shown in Fig. 8,the band 9 is not applied centrally upon the forming member but one edgeof the band is closer to the forming member than the other edge. This isbecause it is desirable in the finished abrasive cover that one edgeportion of the abrasive cover should extend further inwardly than theother e'dge portion, as shown in Fig. 11. The operator in posi tioningthe band 9 upon the forming member II can readily locate the bandin thedesired relation by bending downwardly, as indicated by Y the referencecharacter 23, the upper edge portion of the band 9 to determine whetheror not the edge registers with the'internal suriace of the formingsigned hen the edge of the band, thus regmber. The forming member is sodeone and one-halfeinches in width.

The apparatus'for expanding the forming member is shown in Figs. 12 and13. This apparatus comprises a fixed circular base plate 25 on which acoaxial movable plate 21 in the form of an annulus is mounted. The plate21 has a circumferential flange 29 by which itis retained in coaxialrelation with'respect to the base plate 25. The base plate 25 has formedtherein two slots 3| at right angles to each other and each extendingdiametrically across the base plate. In each slot 3| there are movabletwo slide bars 33 retained in the slot 3| byscrews 35 the stems of whichare capable of sliding in narrow slots 31 in the base plate 25 and theenlarged heads of which are capable of sliding in wider slots 39 in thebase plate. end of each ofthe four slide bars 33 is provided with asegmentally-shaped member 4| which upstands'above thesuri'ace of thebase When the forming The inner plate 25 and is secured to its slide bar33 by -a screw 43 and pins 45. Each slide bar 33 has, near its outerend, a cam roll 41 upstanding therefrom and carried by a stud 49 passingthrough the bar and having a nut on its upper end. The rolls 4'! engagein arcuate-slots 53 cut in the plate 21 and above the rolls on the studs49 are washers 55 of larger diameter surface of the plate 21. is alaterally extendin handle 51. The arrangement is such that on rotatingthe plate 27 by means of the handle 51 in a clockwise direction asviewed in Fig. 12 the slots 53 serve to move the cam rolls 41 outwardly.Thus the members M are also moved outwardly in 'unison.

.In the use of the apparatus a forming member II with a band 9 thereuponis placed in the an arcuate strip of metal between the lapping apparatusin the position indicated in Fig. 13, the members 4| being located inthe space within the interior of the forming member and the lowersurface of theband 9 resting against the base plate 25. The handle 51 isthen manipulated to cause the members 41 to move outwardly as alreadydescribed. These members will engage the inner surface of the strip I1,their surfaces which engage the strip being shaped, as seen in Fig. 12,to a curvature in general correspondence with that of the strip i'l whenthe forming member is expanded. The outward motion of the members 4|serves to expand the rubber annulus l3 until, as hereinbefore described,a stage is I reached at which the ends {9 and 2| or thestrip' l1 comeinto abutting relation to maintain the forming member is expandedcondition. The handle 5'! may then be moved counterclockwise and theexpanded forming member removed (claim as new and desire to secure byLetters Patent of the United States is: Y

, the weave or the fabric in bias relation to the circumference of theband, and in shaping the band by an expansive force applied from withinthe band.

2. The method of making an abrasive cover for the rim of a rotary driventool which consists in making a strip of abrasive-coated cloth with theedges of the stripin bias relation to the weave of the cloth, cementingtogether the ends 01 the strip to form a closed band with the abrasivecoatingon the outside, moistening the band,

stretching the band to a desired shape by expansive pressure appliedinternally of the band, and maintaining the band thus stretched whilethe band dries to the desired shape.

3. A device for shaping abrasive bands comprising a ring of rubberadapted to engage the interior of an abrasive band and to be expanded tostretch the-band, and a ring of resilient metal within said rubber ring,the ends of said metal ring overlapping when the rubber ring is un--expanded and abutting when the rubber ring is expanded, said metal ringwith its ends in abut-' tinggrelation' serving tomaintain said rubberring expanded. a

4. VA device according to claim 3 including also ends of the resilientmetal band and the interior of the rubber ring.

5. An apparatus ,for shaping abrasive bands comprising a ring of rubberadapted to engage the interior of an abrasive band, means for expendingsaid ring tocause said ring to stretch the band, and means formaintaining said ring expanded after removal from said expanding means.

6. An apparatus disks having guideways extending outwardly from itscentral portion and the other disk having cam elements and having acentral opening, a slide retained in each of said guideways by saiddisk, means onsald slides in co-operative engagement with saidcamelements to cause outward or expanding movement of said slides uponrelative rotation of said disks, and a member carried by each slidehaving an arcuate bearing surface adapted to engagethe interior of anarticle to be expanded, said work-engaging members extending through thecentral opening of.; said cam disk, and said arcuate surfaces when thework-engaging members are expanded having'a common center in the axis ofsaid disks.

FRANK NOWN.

for,stretching abrasive bands comprising a pair of coaxial disksconstructedv and arranged for relative rotation, one of said

